Field of the Disclosure
The present disclosure relates to an amplifier circuit and a detection apparatus including the same, and more specifically to an amplifier circuit that converts a charge signal into a voltage signal and to a detection apparatus including the amplifier circuit.
Description of the Related Art
Piezoelectric devices are used for the detection of, for example, vibration, torque, and weight. A piezoelectric device outputs a charge signal as a detection result. A charge amplifier circuit is used to convert the charge signal from a piezoelectric device into a voltage signal. Such a charge amplifier circuit is disclosed in, for example, Japanese Unexamined Patent Application Publication No. 3-182109 (Patent Document 1).
As an apparatus for detecting vibration, a detection apparatus that detects the state of a subject is proposed where the state of the subject is detected using a sensor attached to, for example, the body of the subject. For example, Japanese Unexamined Patent Application Publication No. 2009-279122 (Patent Document 2) discloses a state detection apparatus that detects swallowing or a cough of a subject.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 3-182109.
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2009-279122